1. Field of the Invention
The present invention relates to a method of recording data on a card-like record medium such as an optical card and a magnetic card.
2. Prior Art
As for the card-like record medium, the magnetic card and the optical card are known. Since these record mediums are portable, the magnetic card is widely used for a credit card and a prepaid card, and the optical card having larger storage than that of the magnetic card is expected to be used for a bank card and a portable map.
The optical card disclosed in for example PCT/US82/00187 has a large storage as mentioned above. Therefore, when the data are recorded on a plurality of tracks successively, a recording operation is performed by moving the optical card and a recording head relatively and reciprocally.
In this case, a time required for recording the data is shortened as compared with a one-way recording operation. However, as shown in FIGS. 7A and 7B in which for example the data recording operation is performed by moving an optical card 1 reciprocally with respect to a recording head 2, if the data recording operation is performed in both directions i.e. a normal direction shown in FIG. 7A and a reverse direction shown in FIG. 7B in such a manner that the data are recorded on respective tracks 3 in the same direction and same modulation method, the data recording direction is varied track by track. In this case, if a data reading operation is performed in only one direction as usual, the data cannot be readout accurately.
To eliminate the drawback mentioned above, as shown in FIG. 8, it is possible to read the data by utilizing flags 5 and 6 arranged in top and bottom portions of data block 4 and representing the recording direction of the data block 4. However, in this method, since it is necessary to use regions for recording the flags 5 and 6, an amount of recordable data in respective tracks 3 is decreased. Moreover, since it is necessary to use a circuit for recording the flags 5 and 6 and a circuit for detecting the flags 5 and 6 on the reading operation, a device becomes expensive in cost. Further, if the flags 5 and 6 are not detected accurately due to a defect of the optical card such as a flaw or an adhesion of dust to the optical card, all the data in the data block 4 which occurs the reading error cannot be readout at all.